Abrasive-throwing wheel



June 18, 1940. l D. c@ TURNBULL 2,204,633

ABRASIVE THROWING WHEEL Filed Nov. 17, 19:56 2 sheets-sheet 1 iff Il!!!IH Hl INVENTOR ATTORNEY June 18, 1940. D. c. TURNBULL ABRAsIvE THRowINGWHEEL Filed Nov. 17, 1936 2 Sh eets-Sheet 2 wx mm um .Se w

ATTORNEY Patented June 18, 1940 UNITED: STATES`- yParrain" OFFICE2,204,633- ammslvE-'rnaowmo WHEEL David` C. Turnbull, Mishawaka, Ind.,assignor to American Foundry Equipment Company, Mishawaka, Ind., acorporation of Delaware This invention relates to abrasive-throwingwheels, and more particularly to improved throwing blades for use insuch wheels.

Certain details of the shape of the abrasive I` throwing blades, shownin this application, are claimed in my copending application, Serial No.124,815, filed February 9, 1937.

Abrasive-throwing wheels in general used in the cleaning of metalliccastings, forgings, bars, billets, sheets and like materials, operate tothrow under ydirectional control and against a surface to be cleaned,the abrasive material which generally comprises cracked steel grit,steel shot, or quartz sand. The abrasive-throwing wheels must l berotated at a speed suficient to hurl the abrasive from the wheel atvelocities of 9,000 to 16,000 feet per minute.' It is desirable that thewheel be so constructed as to permit asmooth and uniform flow of theabrasive through the wheel `and c that such parts of the wheel as comeinto contact with the abrasive should be composed of a material which isas resistant as possibleto the eroding action of the abrasive.

structurally, the abrasive-throwing wheels now in commercial usecomprise a series of throwing blades generally of channel form, whichextend from the periphery of the wheel inwardly short of the rotatingaxis of the -wheel so as to dene a central space or opening. Directionalprovision of a tubular control member which extends into the centralopening and is provided with a discharge opening in the circular wallthereof of predetermined butlimited peripheral length. Suitable meanssuch as an impeller, comprising a series of radially arranged varies,project the abrasive fed into the tubular control member through theperipheral opening thereof. 'Ihe impeller is preferably mounted torotate with 40 the blade, the tubular control member normally remainingstationary during rotation of the Wheel but otherwise adjustably mountedso as to control the direction of flight of the abrasive thrown from theWheel. The blades may be rotatably supported or mounted upon a side wallplate or a pair of spaced side wall plates, as desired.- the side wallplates being connected to the drive shaft. My improved bladesare'preferably mounted substantially along a radial line extending fromthe -axisof rotation of the wheel, and are each provided with arelatively thin lip portion which extends forwardly or in the directionof rotation of the wheel. The thixr lip operates to cleanly scoop up theabrasive ejected from the discharge opening in the control member andpercontrol of the abrasive is accomplished by the c mits it to passalong the advancing face of the, blade. Since. the greatest wear on theblades occurs along the outer end of the blades dueto the increasingspeed of the abrasive moving thereacross', I preferably `graduallyincrease the thick-v ness of the blades from a point adjacentthe lipportion to the outer end of the blades. portion is so shaped anddesigned that the abrasive is given little or'no opportunity to strikethe inner end of the blades and rebound inwardly against the outersurface of the tubular control member, but is required to pass eitheronto the advancing face of the adjacent blade passing over the dischargeopening of the control member, or otherwise passing to the rear of saidblade and then onto the advancing face of the next succeeding blade.Thus a smooth and evenow of abrasive through 'the wheel is obtained. Theside wall plates,4 if the wheel is` properly constructed, receive verylittle, if any, wear due to the fact that the abradant is confinedWithin ltheside walls of the channel-shaped blades in its passage fromthe opening of the control member to the periphery of the wheel. Anysidewash `from the abrasive-discharge outlet adjacent the.

center of the wheel substantially without spattering, which bladepossesses great strength and wear resistance where eroding action of theabradant is greatest, and which is conducive to a smooth and uniformflow of abradant over the surface of the blade.

Various other features and advantages `of the invention will be apparentfrom the following particular description and from anrinspection of theaccompanying drawings. v

Although the novel features which are believed to be characteristic ofthis invention will be particularly pointed out in the claims appendedhereto, the invention itself, as to its objects and advantages, and themanner in which it may be carried out, may be better understood byreferring to the following description taken in coning a part thereof,in which y i Fig. 1 is a side view of the abrasive-throwing wheel as itvappears when assembled; this view` showing my-improvedabrasive-throwing blade The lip Vnection with the accompanying drawingsformbroken away more clearly to illustrate the construction; v

Fig. 2 is an end view of the wheel shown in Fig. 1;

Fig. 3 is 4a transverse cross-sectional view through the wheel taken online 3-3 of Flg. 1;'

Fig. 4 is an enlarged fragmentary perspective vlew showing a 'portion ofthe tubular control member and the adjacent ends of the throwing blades;

Fig. 5 is a perspective view of my improved throwing blade looking atthe advancing face thereof; and` Fig. 6 is a perspective" view of thethrowin blade looking at the rear face thereof.

Similar reference characters refer to similar parts throughout theseveral views of the drawings and the specification.

The' abradant use d in abrasive-throwing wheels necessarily must possessa high cutting or abrading efciency in order to economically andsatisfactorily clean, polish, harden, or otherwise treat hard metallicsurfaces, such as castings, forgings, billets, bars, sheets, and likematerials, which materials are generally coated either with a very hardblue scale or with hard crusty matter adhering to the surface of themetal after casting, forging, or rolling the same. To remove thisvundesirable scale and foreign matter successfully it will beappreciated that an unusually hard abradant material must be used'.v andprojected against the surface to be cleaned at abrading velocities. Inordinary cleaning operations, either cracked steel grit, steel shot, orhard quartz sand or various mixtures thereof, is used as the abradant.Where an abrasive-throwing wheel is used to project the abradant, suchwheels must be rotated at very high speed in order to project from thewheel the abradant material at satisfactory abradant velocities ranginggenerally from 9,000 to 16,000 lineal feet per minute. By way ofexample, successful abrasivethrowing wheels have been constructed havinga diameter of approximately 20 inches, which wheels are rotated atspeeds from 2,000 R. P'. M. to 3,000 R. P. M. and upward to transmit tothe abradant the desired abradlng velocity. In wheels of approximatelytwenty inches in outside diameter, tubular control members have beenused varying in diameter from approximately four inches to approximatelynine inches and over, and the blades of such wheels have consequentlyvaried in radial length from approximately five to approximately eightinches. It will be appreciated that at such high velocities as abovementioned the labradant exerts a considerable eroding action on suchparts of the wheel which come into contact with the abradant, andparticularly those parts which are farthest removed from the axis ofrotation. This abrading action is particularly severe on the throwingblades and particularly towards the outer ends thereof.

positioned within the wheel, certain parts being dant smoothly andevenly over the 'surface thereof. Thus by increasing the life of thewearing parts, and particularly theV throwing blades, the

- abrading unit can be operated for a considerably greater length oftime without shutdown for replacement and repair. Y

There is shown for purposes of illustration in Figs. 1 to 3 inclusive ofthe drawings, one type of abrasive-throwing wheel embodying myimprovements herein described. Generally, the wheel may comprise a rearside wall disc I and a front side wall disc 2 aconnected together by aplurality of stud elements 3 suitably secured to the side wall discs Iand 2. lThe wheel is mounted on va rotatable shaft d having `a hub 5connected by means of bolts 6 to the disc I. My improved throwing bladesbV extend from the periphery of the wheel inwardly short of the rotatingaxis so as to provide a central opening orv chamber c. Each blade isformed from a hard wear-resisting material which will be presentlydescribed, each blade generally comprising a bottom portion I and sideflange portions IIlI, providing a channel-shaped member adapted toretain the abrasive therein as it moves across the face thereof. Theflange portions IUI of the blade may be arranged to seat withincorresponding grooves l provided in the side wall discs I and 2 of thewheel. Removable screws 3l provided with inner tapered portion 32project through the side wall discs I aind 2, and engage the undersurface of the blades b to retain the blades in xed position vwithin thewheel, with the flanges IIlI in abutment against the overhangingshoulders 8. The blades may each be provided with a grooved recess I02into which the tapered end of the screws 3| project.

A tubular control member I0, which may have an inwardly extending flangeII at the inner end thereof, extends into the central chamber c. Thecontrol member I0 is mounted independently of the throwing blades b andthe side wall discs I and 2 on a suitable support I2. An impeller ismounted within the control member and xed to rotate with the wheel. Theimpeller may comprise a rear side plate I and a front side plate I6connected by a plurality of radiating impeller vanes I1. The impellermay be connected to rotate with the wheel by means of a bolt I8 whichscrews into the blade centering plate I9 fixed to the rear side walldisc l by means of screws 2I. Abrasive flows from a feedpipe 50 into theimpeller through the center opening 22 in the front side plate I6 of theimpeller. The abradant drops radially across the impeller vanes I1 andis then whirled Within the tubular 'the abrasive or to the inner ends ofthe blades.

The abrasive gains momentum as it moves across the face of the bladesand is thrown fromthe outer ends of the blades with great force. Underthe same operating conditions, a fixed relationship exists between theclock dial position of the discharge opening o in the control member Illand the clock dial'position of the arc of clis-y charge fromv the wheel.By adjusting the position of discharge opening o, the direction of theof the blades.

abradant thrown by the wheel may be regulated and controlled. Theposition of the discharge opening o is adjusted by rotating the controlmember I which brings the discharge opening l I tends relatively closeto the exterior surface of the tubular control member l0, su-ilicientspace being allowed for free clearance only. The lip |03 extends fromthe control member1|0 in the direction of rotation of the wheel. Theback surface of the lip |03 is beveled as at |0312 with respect to theback face of the blade, and the front face 03a of the lip is beveledandslightly rounded so as to smoothly roll into the advancing face ofthe bottom portion |00 of the blade.

The thin lip |03 serves to cut.the abrasive stream discharging from thedischarge opening o of the control member |0 so as to avoid anyinterference with the free movement of the abrasive onto the advancingface of the blade. The inner end of the blade lip |03 is preferablyapproximately only 1A; to 1A@ of an inch or less in thickness so thatthe abrasive ejected from the discharge opening o has little or noopportunity to be deflected by the inner end of the lip |03 inwardlyagainst the outer surface of the tubular control member. Thus, theabrasive discharged from the opening o either passes clear of or glidesin contact with the advancing face |03 of the lip, or passes under therear face |0312 of the lip, from whence it will pass directly onto theadvancing face of the succeeding blade. Thus, inward sputtering` of theabrasive is avoided. Also, the construction of the blade above describedis conducive of a uniform spread of the abrasive over the entire widthof the blade, avoiding a side-wash of the abrasive along one side oftheblade asit moves over the same. Sidewash is further prevented bytapering the inside face I0|a ofthe side walls |0| for a distanceadjacent the inner end, as' shown in Fig. 5. The tapered surfaces |0|aof the side Walls |0| assist in distributingthe abrasive deposited ontothe adb vancing face of the blade uniformly over the width of theadvancing blade surface.

It is known that the eroding effect `of the abrasive increases as itsspeed or velocity over the bladeincreases, resulting in greater wear ofthe blade at the outer end thereof. The life of the blade can bematerially increased by gradually increasing the 4thickness of the bladetoward the outer end thereof. As shown more particularly in Figs. l, 4,5 and 6, the blade bottom |00 gradually increases in thickness fromadjacent the inner end where it may be approximately 11g to $46 of aninch in thickness to the outer end of the blade .where it isapproximately 15s of an inch in thickness. Tests have indicated that thelip |03 approximately 11g of an inch in thickness,

as well as the inner end of the bottom .|00 ap proximately 1%@ to $56 ofan inch in thickness, will last as long as the outer end of the bladehaving a bottom wall thickness of approximately 11; of an inch. Testshave further -illustrated that when the blade is also made of materialabout to be described, a blade life of from 60 to 100 hours ofoperation, and over, may be realized.

In accordance with this invention, the wearing parts of theabrasive-throwing wheel, such as the impeller vanes the tubular controlmember I0, and particularly the abrasive-throwing blades b, are formedfrom a composition containing 'pure iron intermixed with variouscompounds providing a 'metallic composition highly resistant to abrasivewear, yet tough and able to withstand the impact and shocks incident tooperation. The material further possesses a high degree of structuraluniformity so that Wear will occur in the material smoothlyanduniformly. The material can be economically produced and cast intothe desired form at relatively low cost.

More particularly, the metallic composition comprises iron alloyed withcarbon', a metal of the molybdenum ortungsten group, chromium, andsilicon. To the above materials may be added a small amount of maganese.More'particularly, the metallic material may comprise subl stantiallypure iron alloyed with from 1% to 31% by weight of carbon, approximately4 to 6% by weight of metal of the molybdenum or tungsten group,approximately 2 to 6% by weight of chromium,-land approximately one-halfof one percent. (.50%) to 2% by weight of' silicon. The amount ofcarbon, molybdenum or tungsten, chromium and silicon added to the ironmay be varied within the above limits.

'I'he composition is particularly resistant to abrasive wear caused bythe rapid movement of the abrasive material such as steel grit, steelshot, and quartz sand, over thecomposition surface. The composition issusceptible of being cast to form the desired part of theabrasive-throwing f wheel, whether it be the impeller. the tubularcontrol member |0, or the outer abrasive-throwing blades b. Thecomposition formed from the ingredients above specified and thus cast isunusually uniform in granular structure, so that the abrasive-throwingwheel parts formed from the composition will wear with great uniformity.

It has heretofore been attempted to form abrasive-throwing blades ofsuch material as chilled iron, rubber, and a silicon compound intermixedwith the iron. not proven satisfactory since they are unable to standthe repeated impacts of the rebounding shot and abrasive. Tungstencarbide and chromium carbide must be intermixed with the iron inexcessive proportions to produce a material of substantial wearresistance. These compounds are very expensive and must be present insuch large proportions as to make the material almost prohibitive inprice. Furthermore with the compounds above mentioned, ithas beenirnpossible to produce a `blade material of sufllcient structuraluniformity so as to wear evenly, and

the blades so' made soon become pitted andthe tubular control member l0,and such other,

parts of the wheel as come into -direct contact with the movingabrasive. Abrasive throwing wheel parts made from my improved metalliccomposition possess unusually high abrasion resistance, toughness,impact-resistance, and

Such materials haveV damping characteristics, a high degree ofstruclength, obtaining maximum and, as shown in Fig. 4,'each. of theimpeller.

vanes I1 is positioned slightly in advance of its corresponding blade b.Since the impeller vanes il rotate at the same R. P. M. as the blades,the

vanes Il throw'out a load of abrasive a through the opening o just intime to be scooped up by the lip |03 as the abrasive a emerges beyondthev opening o. The abradant then moves over the face of the blade withincreasing velocity, the blade bottom being correspondingly thickcnedtowards the outer end of the blade so as to withstand the increasingWear. As thus constructed, the outer end of the blade will be worn tothe point of uselessness about the time that the -lip lr03 is worn tothe point whereI satisfactory operation can no longer be obtained. Thus,it is 'seen that a blade is provided which Wears out substantiallyuniformly throughout its abrading etliciency from the blades.

While certain novel features of the invention have been disclosedV andare pointed out in the annexed claims it will be understood that variousomissions, substitutions and changes may be made by those skilled in theart Without departing from the spirit of the invention. l

What is claimed is:

1. A blade -adapted for -use in centrifugal abrasive throwing Wheels ofthe character ncluding a rotor adapted to be driven at high speeds andcarrying a plurality of radially extending throwing surfaces with meansfor feedi ing abrasives onto the inner ends of said surfaces, saidblades having a propelling surface along which the abrasives may begradually accelerated formed from a metallic compound which is highlyresistant to abrasive wear, impact shocks and metal fatigue incident toprolonged operation in the throwing of steel grits, sand and similarabrasive particles at blasting velocities,

said metallic compound including approximately 2 to 3% by weight ofcarbon, approximately 4 to 6% by Weight of metal of the molybdenumgroup,

approximately 2 to 6% by weight of chromium, approximately one-half ofone percent to 3% by weightl of silicon, 'and the remaindersubstantially pure iron.

2. A blade adapted for. use A incentrifugal abrasive-throwing wheels ofthe character including a rotor adapted to be driven 'at high speedsand-carrying a plurality of radially extending' throwing surfaces alongwhich the abrasives thrown may be accelerated with means for feedingabrasives onto the inner ends of said surface, said blade having arelatively vextensive smooth and continuous abrasive impelling surfaceformed from a metallic compound whichA speeds and carrying a pluralityofradially ex tending throwing surfaces with means for feeding abrasivesonto the inner ends of said surfaces, said blades having a propellingsurface along which the abrasives may be gradually `accelerated formedfrom a metallic compound which is'highly resistant to abrasive wear,impact shocks and metal fatigue incident to prolonged operation in thethrowing of steel grits, sand and similar abrasive particles at.blasting velocities, said compound including approximately 2 to 3% byweight of carbon, approxi'- mately 4 to 6% by weight of a metal of themolybdenum group, approximately 2 to 3% by weight-of chromium,approximately 1 to 2% by Weight of silicon, manganese up to 1% byWeight, an'd the remainder substantially pure iron.

DAVID C. 'I'URNBULL

